'''
By listing the first six prime numbers:
2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the Nth prime number?
'''
from __future__ import print_function

from math import sqrt


def isprime(n):
    if (n == 2):
        return True
    elif (n % 2 == 0):
        return False
    else:
        sq = int(sqrt(n)) + 1
        for i in range(3, sq, 2):
            if (n % i == 0):
                return False
    return True


n = int(input())
i = 0
j = 1
while (i != n and j < 3):
    j += 1
    if (isprime(j)):
        i += 1
while (i != n):
    j += 2
    if (isprime(j)):
        i += 1
print(j)
